Exposure to Di-2-ethylhexyl Phthalate and Benign Prostatic Hyperplasia, NHANES 2001-2008

30% of men suffer from benign prostatic hyperplasia (BPH) worldwide. As one of the most important members of Phthalate esters, previous studies suggested ubiquitous Di-(2-ethylhexyl) phthalate (DEHP) exposure is associated with such male disorders by interfering with endocrine system, however, little is known about the association between DEHP exposure and BPH. The objective of this study was to study the potential association by the 2001–2008 National Health and Nutrition Examination Survey (NHANES) data. The data was collected, and multiple logistic regression was adapted to measure the association. The concentrations of DEHP (∑DEHP) were calculated by each metabolite and split into quartiles for analysis. Results showed that the odds ratio (OR) decreased with increased ∑DEHP concentration. In the crude model, the OR for the second quartile (OR = 1.60, 95%CI [1.24, 2.07]) was obviously higher compared with the lowest quartile. However, the OR for the highest quartile (OR = 0.55, 95%CI [0.44,0.69]) was lower than that for the third quartile (OR = 0.77, 95%CI [0.61, 0.97]), and the OR for the third and the highest quartile were significantly lower than that of the lowest quartile, which suggested biphasic effects of DEHP based on concentration. The results showed the same trend after adjusting confounding factors. The study suggested that the DEHP exposure is associated with DEHP, and the results adds limited evidence to study this topic, however, further researches are needed to determine if the status of BPH can be changed by controlling DEHP exposure.

Overcompensation of CoA Trapping by Di(2-ethylhexyl) Phthalate (DEHP) Metabolites in Livers of Wistar Rats

Di(2-ethylhexyl) phthalate (DEHP) is commonly used as a plasticizer in various industrial and household plastic products, ensuring widespread human exposures. Its routine detection in human bio-fluids and the propensity of its monoester metabolite to activate peroxisome proliferator activated receptor-α (PPARα) and perturb lipid metabolism implicate it as a metabolic disrupter. In this study we evaluated the effects of DEHP exposure on hepatic levels of free CoA and various CoA esters, while also confirming the metabolic activation to CoA esters and partial β-oxidation of a DEHP metabolite (2-ethyhexanol). Male Wistar rats were exposed via diet to 2% (w/w) DEHP for fourteen-days, following which hepatic levels of free CoA and various CoA esters were identified using liquid chromatography-mass spectrometry. DEHP exposed rats showed significantly elevated free CoA and increased levels of physiological, DEHP-derived and unidentified CoA esters. The physiological CoA ester of malonyl-CoA and DEHP-derived CoA ester of 3-keto-2-ethylhexanoyl-CoA were the most highly elevated, at eighteen- and ninety eight-times respectively. We also detected sixteen unidentified CoA esters which may be derivative of DEHP metabolism or induction of other intermediary metabolism metabolites. Our results demonstrate that DEHP is a metabolic disrupter which affects production and sequestration of CoA, an essential cofactor of oxidative and biosynthetic reactions.

Effects of Di-(2-Ethylhexyl) Phthalate At Environmentally Relevant Concentrations On Oxidative Stress and Lipid Metabolism in Livers of Male Xenopus Tropicalis

Di-(2-ethylhexyl) phthalate (DEHP), used as a popular plasticizer to enhance the flexibility of plastics, is a major pollutant in aquatic environments. DEHP poses severe risks to aquatic organisms since it is an endocrine-disrupting compound. To comprehensively evaluate the toxicity of DEHP on the growth and livers of male X. tropicalis, sexually mature male X. tropicalis were exposed to environmentally relevant concentrations of DEHP, 0.2, 0.6, 1.8, 5.4 mg/L, for 49 days. The results showed that DEHP had a severe toxic effect on the livers of male X. tropicalis. Histopathological analysis of livers in all the DEHP-exposed groups showed changes in terms of vacuolization, loose cell cords, and an increasing amount of melanin. Large lipid droplets were markedly formed, and there were changes in the mitochondrial morphology upon DEHP exposure. In addition, oxidative stress was induced through the suppression of biochemical indicators and the downregulation in the mRNA expression of genes (nrf2, cat, sod, gst, and gpx) related to oxidative stress. A reduction in expression of fatty acid metabolism-related genes (pparα) was seen post-DEHP exposure. Thus, our study suggests that the hepatotoxicity induced by DEHP could be attributed to oxidative stress and disordered fatty acid metabolism. In conclusion, long-term exposure to DEHP at environmentally relevant concentrations poses ecological risks to aquatic organisms, which serves as a reminder that the application of DEHP and other plasticizers should be limited.

Effects of Prenatal Phthalate Exposure and Childhood Exercise on Maternal Behaviors in Female Rats at Postpartum: A Role of Oxtr Methylation in the Hypothalamus

Both the detrimental effect of prenatal exposure to di-(2-ethylhexyl)-phthalate (DEHP) and the beneficial effects of physical exercise on brain functions have been reported. The oxytocin pathway has been implicated in the onset of maternal behaviors. Epigenetic modification of the oxytocin receptor gene (OXTR) through DNA methylation has been associated with the pathogenesis of neuropsychiatric disorders. The purpose of this study was to investigate the effects of prenatal DEHP exposure on oxytocin-regulated maternal behaviors and to examine the protective effect of exercise. Pregnant rats (F0) were fed with vehicle or DEHP during gestation and the offspring females (F1) were assessed for their maternal behaviors by pup retrieval test at postpartum. The results showed that reduced pup retrieval activities without significant alteration of stress responses were observed in the prenatally DEHP-exposed females. Prenatal DEHP exposure decreased the expressions of oxytocin, Oxtr mRNA, and oxytocin receptor, and increased Oxtr methylation in the hypothalamus of postpartum female rats. There were no significant effects of exercise on behavioral, biochemical, and epigenetic measurements. These results suggest that prenatal DEHP exposure has a long-term adverse effect on maternal behaviors; Oxtr hyper-methylation may be a potential epigenetic mechanism for this alteration, which cannot be prevented by physical exercise during childhood.

Subacute Exposure to an Environmentally Relevant Dose of Di-(2-ethylhexyl) Phthalate during Gestation Alters the Cecal Microbiome, but Not Pregnancy Outcomes in Mice

Di-2-ethylhexyl phthalate (DEHP) is a plasticizer commonly found in polyvinyl chloride, medical equipment, and food packaging. DEHP has been shown to target the reproductive system and alter the gut microbiome in humans and experimental animals. However, very little is known about the impact of DEHP-induced microbiome changes and its effects during pregnancy. Thus, the objective of this study was to investigate the effects of DEHP exposure during pregnancy on the cecal microbiome and pregnancy outcomes. Specifically, this study tested the hypothesis that subacute exposure to DEHP during pregnancy alters the cecal microbiome in pregnant mice, leading to changes in birth outcomes. To test this hypothesis, pregnant dams were orally exposed to corn oil vehicle or 20 µg/kg/day DEHP for 10 days and euthanized 21 days after their last dose. Cecal contents were collected for 16S Illumina and shotgun metagenomic sequencing. Fertility studies were also conducted to examine whether DEHP exposure impacted birth outcomes. Subacute exposure to environmentally relevant doses of DEHP in pregnant dams significantly increased alpha diversity and significantly altered beta diversity. Furthermore, DEHP exposure during pregnancy significantly increased the relative abundance of Bacteroidetes and decreased the relative abundance of Firmicutes and Deferribacteres compared with controls. The affected taxonomic families included Deferribacteraceae, Lachnospiraceae, and Mucisprillum. In addition to changes in the gut microbiota, DEHP exposure significantly altered 14 functional pathways compared with the control. Finally, DEHP exposure did not significantly impact the fertility and birth outcomes compared with the control. Collectively, these data indicate that DEHP exposure during pregnancy shifts the cecal microbiome, but the shifts do not impact fertility and birth outcomes.

Urine di-(2-Ethylhexyl) Phthalate Metabolites Are Independently Related To Body Fluid Status in Adults: Results From a U.S. Nationally Representative Survey

Background Di-(2-ethylhexyl) phthalate (DEHP) has been utilized in many daily used products for decades. Previous studies have reported DEHP exposure could induce renin-angiotensin-aldosterone system activation and increase epithelial sodium channel (ENaC) activity, which contributes to extracellular fluid (ECF) volume expansion. However, there is also no previous study to evaluate the association between DEHP exposure and body fluid status. Methods We selected 1,678 subjects (aged ≧ 18 years) from a National Health and Nutrition Examination Survey (NHANES) in 2003–2004 to determine the relationship among urine DEHP metabolites and body composition (body measures, bioelectrical impedance analysis (BIA)). Results After weighted for sampling strategy, we reported higher levels of DEHP metabolites was correlated with increases in body measures (body weight, body mass index (BMI), waist), parameters of BIA (estimated fat mass, percent body fat, ECF, and ECF /intracellular fluid (ICF) ratio) in multiple linear regression analysis. The relationship between DEHP metabolites with ECF/ICF ratio were more evident in subjects with younger age (20–39 year-old), women, non-Hispanic white ethnic, and subjects who were not active smokers. Conclusions Besides positively correlated with body measures and body fat, we found urine DEHP metabolites are positively correlated with ECF, ECF/ICF ratio in the US general adult population. It is necessary to do further research to clarify this causal relationship.

Maternal high-fat diet during pregnancy with concurrent phthalate exposure leads to abnormal placentation

Di(2-ethylhexyl) phthalate (DEHP) is a synthetic chemical commonly used for its plasticizing capabilities. Because of the extensive production and use of DEHP, humans are exposed to this chemical daily. Diet is a significant exposure pathway and fatty food contain the highest level of phthalates. The impact on pregnancy following DEHP exposure and the associated interaction of high fat (HF) diet remains unknown. Here we report that exposure of pregnant mice to an environmentally relevant level of DEHP did not affect pregnancy. In contrast, mice fed a HF diet during gestation and exposed to the same level of DEHP display marked impairment in placental development, resulting in poor pregnancy outcomes. Our study further reveals that DEHP exposure combined with a HF diet interfere with the signaling pathway controlled by nuclear receptor PPARγ to adversely affect differentiation of trophoblast cells, leading to compromised vascularization and glucose transport in the placenta. Collectively, these findings demonstrate that maternal diet during pregnancy is a critical factor that determines whether exposure to an environmental toxicant results in impaired placental and fetal development, causing intrauterine growth restriction, fetal morbidity, and mortality.

Epi-mutations for spermatogenic defects by maternal exposure to di(2-ethylhexyl) phthalate

Exposure to environmental factors during fetal development may lead to epigenomic modifications in fetal germ cells, altering gene expression and promoting diseases in successive generations. In mouse, maternal exposure to di(2-ethylhexyl) phthalate (DEHP) is known to induce defects in spermatogenesis in successive generations, but the mechanism(s) of impaired spermatogenesis are unclear. Here, we showed that maternal DEHP exposure results in DNA hypermethylation of promoters of spermatogenesis-related genes in fetal testicular germ cells in F1 mice, and hypermethylation of Hist1h2ba, Sycp1, and Taf7l, which are crucial for spermatogenesis, persisted from fetal testicular cells to adult spermatogonia, resulting in the downregulation of expression of these genes. Forced methylation of these gene promoters silenced expression of these loci in a reporter assay. These results suggested that maternal DEHP exposure-induced hypermethylation of Hist1h2ba, Sycp1, and Taf7l results in downregulation of these genes in spermatogonia and subsequent defects in spermatogenesis, at least in the F1 generation.